1. Field of the Invention
The subject invention is directed to devices for measuring pressures, especially high pressures, and temperatures in a hydraulic or pneumatic system. More specifically, the subject invention concerns devices that incorporate both a piezo-resistive pressure measuring cell and an electronic circuit in one housing to form an integral component.
2. Description of the Prior Art
The usual types of manometers known in the prior art are generally read off at intervals. Furthermore, such devices are frequently inadequate with regard to the precision required for certain measurements. In contrast, electronic measuring devices afford a continuous recording of the measured values and a rapid processing of the signals with a high degree of measuring accuracy.
Hydraulic systems are becoming increasingly complicated in the course of the rapid technical development. One consequence of this is that the hydraulic systems are placing increasingly higher demands on the required accuracy and switching speed of associated systems. As a result, there is a demand for improved pressure and temperature measuring devices that will not only continuously indicate that actual values measured by the electronic circuit, but will also give an instantaneous or real-time indication, of interference in the installation.
In piezo-resistive pressure measuring cells known in the prior art, the piezo-resistive semiconductor element (silicium chip) that is used for recording the pressure is connected to the corresponding contacts by means of binding wires. Thus, the entire sensor housing is standardized from semiconductor technology and is similar to that used for transistors, operational amplifiers, and the like. Consequently, such prior art sensor housings are unsuitable for measuring high pressures because the pressure influence on the housing distorts the measurement. Moreover, the housing often cannot withstand the higher pressures that are to be measured such that it is subject to deformation.
Accordingly, there was a need in the prior art for a pressure measuring device that would measure high pressures and that was also sturdy and could be automatically assembled.
Also, there was a need for a pressure measuring device that could readily be connected to hydraulic or pneumatic systems under high pressure and that would provide a highly accurate measurement.